This is a state requirement. Twice a year schools are required to announce this:

"In order that the right of every pupil to the free exercise of religion be guaranteed within the schools and that the freedom of each individual pupil be subject to the least possible pressure from the Commonwealth either to engage in, or to refrain from, religious observation on school grounds, the school board of each school division shall establish the daily observance of one minute of silence in each classroom of the division.

During such one-minute period of silence, the teacher responsible for each classroom shall take care that all pupils remain seated and silent and make no distracting display to the end that each pupil may, in the exercise of his or her individual choice, meditate, pray, or engage in any other silent activity which does not interfere with, distract, or impede other pupils in the like exercise of individual choice."

See Virginia law here:https://law.lis.virginia.gov/vacode/title22.1/chapter13/section22.1-203/#:~:text=§%2022.1%2D203.,of%20one%20minute%20of%20silence

I don’t know what it says about my general concern for APS that I thought your post was calling for a moment of silence for APS elementary schools in general because things are not looking good …